1. Field of the Invention
This invention relates to a surgical device for obtaining biopsies of soft tissue. More particularly, the invention relates to a minimally invasive biopsy device and a method for its use. The device of this invention is especially useful for obtaining biopsies of small breast tumors. In addition to being useful for diagnostic biopsies, the device of this invention may also be used for therapeutic removal of small malignant or benign tumors, a procedure sometimes referred to as "lumpectomy."
2. Description of Background Art
Early detection of breast cancer greatly improves a patient's prognosis. With the increasing use of mammography, ultrasound and other diagnostic procedures in preventive medicine, breast tumor biopsies are becoming a common surgical procedure. It is estimated that nearly two hundred thousand breast biopsies are performed in the United States each year.
Breast tumors are often detected during a routine mammographic examination. An occult lesion which is too small to be detected by palpation may be detected by mammography. While mammography provides a means for detecting and locating such lesions, it does not provide any meaningful indication of whether the abnormal tissue contains malignant or benign cells. Currently, such a diagnosis can only be accomplished by histologic examination of surgically removed tissue.
A variety of techniques exist for taking a breast biopsy. A needle or core biopsy involves inserting a biopsy needle (e.g., a Travenol Tru-Cut needle) into the lesion and removing a small amount of tissue for examination. This procedure has certain disadvantages, including the possibility of false-negative diagnoses as a consequence of obtaining too small a sample. Consequently, physicians often prefer to excise a small (i.e., less than about 1.5 cm in diameter) lesion completely. Indeed, when such a lesion is excised, it is desirable to include a 1-2 cm margin of tissue around the lesion to minimize the chances that any abnormal cells will have been missed and as a clear margin for treatment of malignancy.
Although small breast tumors can be detected radiologically, they are often difficult or impossible for the surgeon to locate during a biopsy procedure without some type of mechanical aid. Techniques have been developed to assist the surgeon in locating the tumor. For example, a needle may be inserted into the mammary tissue, with its end precisely placed in or near the abnormal tissue. Placement of the needle is accomplished using mammography or ultrasound. The patient is then moved to the surgical suite with the needle in place. The needle guides the surgeon to the area to be biopsied. A related technique involves the use of a thin wire having a barb or anchor on its end. The barb or anchor is placed in or near the lesion, with the aid or mammography or ultrasound, and the wire extends through the skin. The surgeon is guided to the location of the tumor by the wire. This latter technique is described by Kvavle et al. in U.S. Pat. No. 4,007,732.
Various devices have been developed to assist the surgeon in obtaining a percutaneous biopsy. For example, Baylis et al., U.S. Pat. No. 4,177,797, Haaga et al., U.S. Pat. No. 5,477,862 and Kornberg et al., U.S. Pat. No. 5,353,804 describe variations of a biopsy device that employs a stylus or pointed element surrounded by a cylindrical cutting tool. The stylus serves to penetrate the tissue and locate the instrument near the lesion. The biopsy is then obtained by sliding the outer cylindrical cutting tool along the stylus and beyond its point so as to make a cylindrical incision around the lesion. U.S. Pat. No. 4,007,732 describes a biopsy device which consists of a cylindrical cup-shaped cutting tool attached to a hollow shaft. A guide wire that is anchored in the lesion is passed through the shaft of the device and serves to guide the device to the lesion. The utility of these devices appears to be limited to obtaining diagnostic biopsies.
Notwithstanding such devices, the standard breast biopsy procedure remains the freehand technique in which the surgeon makes an incision with a scalpel and removes a roughly spherical mass of tissue using a scalpel, scissors and/or an electrocautery device. The freehand technique suffers from several disadvantages. First, incisions must be relatively large, which results in unnecessary scarring and the possibility of post-operative complications. Second, freehand surgery takes a relatively long time--on the order of 20-40 minutes--adding to the expense of the procedure and the risk of complications resulting from anesthesia. Third, freehand surgery is attended by a small but significant risk of missing a portion of the lesion.
There is, therefore, a need for a biopsy device that overcomes these disadvantages and which also can be employed for therapeutic removal of a small tumor in a single operation.